On Thu, May 15, 2008 at 11:38:59PM +0200, Steffen Schulz <[EMAIL PROTECTED]> wrote:
> - There are published algorithms for good PRNGs, no need to help > yourself with adding unintialized memory and praying the OS does a > good job already. Nothing in OpenSSL has ever *relied* on uninitialized memory. The only job expected from the OS is providing something readable, such as (initially) a bunch of 0x00 bytes. OpenSSL merely *accepts* uninitialized memory, since it sometimes may very well contain some information dating back from whatever happened previously during the program execution that couldn't be predicted by adversaries, in which case this memory would be a good source of entropy. In its internal entropy estimation tally, OpenSSL never assumes that uninitialized memory contributes anything -- this is just opportunistic randomness if you will. This much, by the way, should be very clear to anyone who has read the OpenSSL PRNG's source code comments ;-) Anyone who'd look at the calling code responsible for the Valgrind warning would have found a comment regarding this peculiar behavior. An attempt to understand what is going on locally based on just a single line, however, clearly is doomed. But even looking just at the single function would have shown that the modified version of ssleay_rand_add() doesn't ever dereference or pass the "buf" pointer; this should strike as odd even if you don't read any of the comments. Of course, mistakes can always happen anyway, and to anyone. The motto "never fix a bug you don't understand" will only help you out if you are aware that you don't understand the bug -- not if you think you understand, but actually misunderstand. Bodo -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
